Concentration of metalliferous ores by froth flotation



Patented Feb. 28,1939

omcrmrron 0F manna-snows ones-BY mom rno'rs'non omens; n; Keller, so: Francisco, Calif, assimor to Minerals 8eparation North American Cerporation, New York, N. Y.. a corporation 0! No- Drawing.

Application December 18, 1937, Serial No. 180,549

25Claims. (Cl. cos-46s) This application is a continuation in part of is an aliwl or aralb'l group, depending on the application Serial No, 146,611, filed June s, 1937. The present invention relates to improvements in the Iroth flotation concentration or metal-.

liierous ores/especially sulphide ores.

In my United States Patent No. 1,554,216, issued September 22, 1925, a. process for the concentration of ores by'flotation is described, which is es-' the combinationof xanthic acids with molybdic acid are extremely elective agents in the flotal6 vtionooncentration of metalliierous ores, concen trates of a high degree of purity being obtained bytheirusc. ,Thisis'particularlythe casewith ores. containing-molybdenum sulphide. It is very difficult to obtainimoiybdenite concentrates of sufliciently highgrade by the use of heretofore known flotation agents. especially when the crude moiybdenite-containing ore also contains gans minerals of the class called hydrous micas, such as sericlte. However, by the use 01' the xanthomolybdic acid compounds of the present invention, molybdenite concentrates of a very high grade can be obtained, even in the case 0! ores containing the gangue minerals stated The invention is, of course, not limited to the treatment of molybdenum-bearing ores, but may also be employed with improved results in the concentration of other .metsilifercus c-rcs', such as those of lead, copper, zinc. gold, and silver.

The xanthomolybdic acid compounds of the Present invention can be prepared by acidificationoi an aqueoussolution oixanthete and molybdate respectively present therein in proportions equivalent to two molecules of zanthic acid and one molecule oi molybdic acid. As the xanthate,

any one of various :rauthates in the form of alkali salts may be used, such xanthates including sodium ethyl xenthate, potassium amyl xanthate, potassium octyl xanthate, potassium phenyl-ethyl xantnnte, etc. Pricmolybdate may be any soluble salt of molybdic acid, such as am- 'monium molybdate or sodium molybda-te. Upon acidification, preferably with a mineral acid, 01' the stated solution of :canthate and molyhdme, the desired xanthomolybdic acid compound is precipitated as a dark purplish oily liquid which. on standing; solidifies to a very dark colored amorphous mass. The formu a, for the xant-ho molybdic acid compounds obtained in this mannor appears to be MoO:.(R0.CSSH) 2, wherein R composition of the ranthate used.

For the purpose of acidification, almost any acid can be used. Mineral acids are preferred because they are cheaper and bring about the re- 5 action more rapidly than organic acids, but organic acids can also be used. Satisfactory results have thus been obtained not only with such common mineral acids as hydrochloric acid and sulphuric acid, butalso with such organic acids in as acetic acid, iuroic acid, and.- oxalic acid It has been ioundhowever. that some organic acids, especially those which are substantially insoluble in water, are ineiiectim- Among the mineral acids, sulphurous acid and boric acid have also 15' been iound ineircctive. Ptn'iiication oi the xanthomolybdic acid compoimds oi the present invention can be eiiected by solution in aqueous ammonia and reprecipitation with a suitable acid But this purification need 20 not be carried out prior to use oi the compounds as notation agents, the crude reaction products being quite satisfactory for that purpose.

-A convenient method of preparing the xanthomolybdic acid compounds of the present inven- 25 tion comprises the preliminary step of roasting an ore product containing molybdenite, by which roasting the molybdenum sulphide is converted into oxide. which is then leached out with a solution of caustic alkali to produce a. soluble molyb date. To this liquor is then added the calculated cmozmt of the desired xanthate and the required acid to eii'ect the reaction. Separation of the zanthomoiybdic acid compound thus precipitated, ii desired, may then be eiiected by well-known means. 4

The xanthomolybdic acid compounds of. the present invention are practically insoluble in water, but are soluble in many organic liquids, among which may be mentioned chloroform, ace- 40 tone, and ether. Prior to use of the compounds as flotation agents, therefore, it may be convenlent to dissolve them in a. suitable solvent, which may be one of the three indicated, or any other. But if it is desired to use the compounds in solid form, they may be conveniently added to the ore during grinding so as to become admixed therewith.

solution used in their preparation, without removal of the reaction product. This method ob- 55 viously can be utilized to provide the required amount of xanthomolybdic acid compound continuously in large scale operations.

The xanthomolybdic acid compounds of the present invention are very effective in the flotation of molybdenite from copper-molybdenum ores subsequent to their treatment for a removal of copper sulphides, as in the process described in United States patent to Earl H. Brown, No. 2,070,076, issued February. 9, 1937. In this process copper sulphides are selectively floated away from molybdenite by adding to the ore pulp a small quantity of starch or other protective colloid, acting to depress the molybdenite and inhibit its flotation, other agents being also present in the pulp to effect flotation of the copper sulphides. It has now been found that by subsequent treatment with a xanthomolybdic acid compound of the material remaining after such a flotation of copper sulphides, a molybdenite concentrate can be obtained containing a very small proportion of gangue minerals.

When necessary, of course, theconcentrates initially obtained by the use of the xantho- 'molybdic acid compounds of the present invention can beimproved in grade by retreatment in the usual manner.

. I have found that it is possible to employ the xanthomolybdic acid compounds of the present invention in acid ore pulps, as well as in pulps of a neutral or alkaline character. They are therefore very useful in the flotation of metallic values from materials that have been subjected to hydrometallurgical processes.

The xanthomolybdic acid compounds of the present invention are employed essentially as collectors. To any one skilled in the art, however, it is obvious that they can be used in conjunction with other collectors, such as xanthates or dithio phosphates. And they may be used, of course, with such additional flotation agents as frothing agents, inhibiting agents, activating agents, etc.

Examples will now be given describing certain tests which have been made in carrying the invention into effect, it beimg understood that the various reagent proportions indicated in each example are expressed in the usual manner as pounds per ton oi dry material treated.

Example 1 A 1000 gram sample of Nevada Consolidated Copper Company ore, of a parti e size to pass IO-mesh, was reground wet for four minutes in a ball mill with 12 lbs. of lime per ton of ore. The material thus initially treated was transferred to a laboratory size subaeration flotation machine where it was conditioned by agitation with 0.1 lb. of pine oil per ton and 0.02 lb, of ethyl xanthomolybdic acid per ton, the latter agent being added as a solution in acetone. Subsequently, the pulp was treated in the machine for the production of a froth, which was removed in the usual way. The results of the test are shown in the following table:

Percent Assay, per- Distribution, weight cent Cu percent Cu Heads 100. 0 i. ll 100.0

Example 2 another 1000 gram sample of the same copper ore,

but with 0.1 lb. of amyl xanthomolybdic acid per ton replacing the ethyl xan'thomolybdic acid of that example. Substantially the same results were obtained, as shown by the following table:

Here 0.10 lb. of butyl xanthomolybdic acid per ton was used instead of the ethyl xanthomolbydic acid of Example 1. All other conditions were exactly the same as before, the test being carried out on still another 1000 gram sample of the same copper ore. The following table indicates that again similar results were obtained:

Percent Assay, aer- Distribution, weight cent u percent Cu Good results were also obtained when octyl xanthomolybdic acid was substituted for ethyl xanthomolybdic acid on a similar copper ore.

Example 4 A 1500 gram sample of a similar copper ore, in

the form of a pulp of 50% solids, was reground for five and one-third minutes with 5 lbs. of lime per ton. Conditioning of the reground ore was in this instance carried out with a mixture obtained by adding hydrochloric acid to admixed Percent Assay, (per- Distribution, weight cent 11 percent Cu COMPARATIVE TEST 1 Another 1500 gram sample of the same copper ore as in Example 4 was processed in the manner described in that example, but omitting the use of the ethyl-xanthon1olybdic-acid-containing mix- I ture. Instead, 0.04 lb. of sodium ethyl xanthate per ton of ore was added to the reground ore, the procedures being otherwise exactly the same. The results in this instance were as follows:

Percent Assay, Distribution,

weight percent Cu percent Cu Heads 100. 0 1. 10 100. 0 Conc 4.49 22. 30 91. 29 1 Tail 95. 51 0. l0 8. 71

COMPARATIVE Trcs'r 2 In this test, employing still another 1500 gram sample of the same copper ore, its conditioning 7 following results were obtained:

Percent Assay, weight percent Cu percent Cu Distribution,

Heads 1 100 no Ewen 16 Example A 1000 gram sample of -mesh Desloge Lead Company ore was reground in the ball mill for fifteen minutes at about 50% solids with 1 lb. of soda. ash per ton. To the reground ore, in the 20 flotation machine, was then added a mixture obtained by adding a 0.9% solution of sodium molybdate, acidified with hydrochloric acid, to a 1% solution of sodium ethyl xanthate, the quantitles of the solutions being adjusted so as to form 0.04 lb. of ethyl xanthomolybdic acid per ton. Cresol was also added at the rate of 0.1 lb. per ton. Preliminary agitation was carried out with these reagents, subsequent towhich a flotation concentrate was removed in the usual manner.

The following table indicates the results of the test.

Percent Assay, per- Distribution, weight cent Pb percent Pb 100. 0 I 4. 5a 100. o 8. 46 52. 0 96. 0 iii. 54 0. 2 4. 0

Conmmrrvs TEST 3 Employing another 1000 gram sample of the same lead ore as in Example 5, the procedures of that example were repeated with the ethyl-xenthomolybdic-acid-containing mixture replaced by amixture obtained by mixing a solution of sodium molybdate, acidified with hydrochloric acid, with a solution of potassium secondary butyl xanthate, which solutions were used in quantities to produce 0.3 lb. of butyl xanthomolybdic acid per ton. Preliminary agitation was carried out with the said mixture, together with 1 lb. of copper sulphate (CUSO4.5H20) per ton and 0.3 lb. of pine oil per ton; subsequent to which a floating froth was produced and removed in the usual manner. The results are shown in the following table:

Percent Assay. r- Distribution, weight cent 11 percent Zn Percent Assay Distribution,

weight percent n percent Zn Heads -l 100. 0 14. 9 100. 0

22. 97 (i2. 8 96.89 77.03 0. 6 3. ii

COMPARATIVE T551 6 On still another 1000 gram sample of the same zinc ore as in Example 6, with no other agent than the copper sulphate and pine oil of that example, all other conditions remaining the same, the following results were obtained:

Percent Assay, Distribution,

weight percent Zn percent Zn 0.04 lb. of sodium ethyl xanthate per ton, the re- 5 WM suits of this test being as follows: 323?:1'523312133232112: $333? 31% it?! 1353?? 23??? giiti tt Example 7 A 1000 gram sample of 10-mesh Mexican Canmmt m0 4 0M delaria. ore, containing gold and silver, was re Conc -IIIII I.IIIII-- 7.48 58.2 94.7 ground wet in the ball mill and thereafter trans- 52 M5 ferred to the flotation machine. Conditioning in the machine was then carried out with 0.2 lb.

55 Conmanrvs TEST 4 of pine oil per ton, 0.1 lb. of cresol per ton, and

Still another 1000 gram sample of the same lead ore as in Example 5 was taken, which sample subsequent to regrinding with soda ash was conditioned with cresol only. The conditions were otherwise the same as in that example, including the amounts of soda ash and cresol, the following results being obtained:

Percent Assay, per- Distribution,

A 1000 gram sample of 10mesh Joplin zinc ore was reground wet in the ball mill for ten minutes and thereafter transferred to the flotation machine. There was then introduced into the pulp Assay in oz/ton Percentdistributicn Percent weight Au Ag Au Ag Heads 100. 0 0. 743 33. 2 "X 100. 0 Cone 3. 659 18. 751 763. 86 91.44 84. i8 Tail w 96. 341 0. 066 5. 45 8. 56 i5. 82

COMPARATIVE TEST 7 Employing another 1000 gram sample of the same gold-silver ore as in Example '1, the procedures of that example were repeated, substituting for the amyl-xanthomolybdic-acid-containing mixture 0.2 lb. of potassium amyl xanthate per ton, the following results being obtained:

On still another 1000 gramsample of the same gold-silver ore as in Example 7, the following results were obtained employing as agents the pine oil and cresol only of that example:

Assay in oz/ton Percent distribution Percerng weig Au \g Au Ag Heads 10b. 0 0. 694 as. 46 100. o 100. 0 Cone 2. 267 11. 614 866. 69 39. 07 53. 89 Tail 97. 733 0. 42 17. 2 60. 93 46. 11

Example 8 A 1500 gram sample of Climax Molybdenum Corporation ore, of a particle size to pass 10 mesh, was reground wet in the ball mill for fifteen minutes. Preliminary agitation of the reground ore was then carried out in the flotation machine with 0.27 lb. of sodium cyanide per ton, 0.034 lb. of 'terpineol per ton, and a mixture obtained by adding a solution of sodium molybdate, acidified with hydrochloric acid, to a solution of SOCllllll'l ethyl xanthate, which solutions were used in quantities to form 0.2 lb. of ethyl xanthomolybdic acid per ton of ore. Thereafter, the pulp was subjected to froth flotation in the usual mannler, the results being shown in the following table:

tical manner, except that the use of the ethylxanthomolybdic-acid-containing mixture was omitted, the sodium cyanide and terpineol only of that example being used. The results in this instance were as follows:

Distribution Percent Assay, perweight cent Mos; figgg Heads 100. 0 0. 79 100. 0 Cone 0. 887 60. 0 67. 37 Tail 99. 113 0. 26 32. 63

Example 9 A sample of IO-mesh Miami Copper Company ore, containing both sulphide and oxidized copper minerals, was reground wet in the ball mill for ten minutes and thereafter transferred to the flotation machine. Preliminary agitation of the material in the machine was then carried out with 0.1 lb. of pine oil per ton, and a mixture obtained by mixing a solution of sodium molybdate, acidified with hydrochloric acid, with a solution of sodium ethyl xanthate, the quantities of which solutions were adjusted to yield 0.04 lb. of ethyl xanthomolybdic acid per ton of ore. Frothing was then carried out in the machine, yielding a concentrate of sulphides. The remaining pulp was then removed from the machine,

' thickened, and leached with sulphuric acid to dissolve oxidized copper, the dissolved copper being then precipitated in the pulp in the form of metallic copper by addition of metallic iron. Thereafter, upon return to the machine, the pulpwas reconditioned with 0.1 lb. of pine oil, 0.1 lb. of Barrett No. 4 flotation oil, and 0.26 lb. of ethyl xanthomolybdic' acid as a mixture prepared in the same manner as above indicated in this example, all per ton of dry ore. Frothing was then resumed and a cement copper concentrate separated. The results obtained are shown in the following table, wherein the tailing refers to the material remaining after the second flotation operation:

' Percent Assay, b Distribution,

weight cent u percent Cu Hes 100. 0 2.41 100.0 Cu sulphide conc 2.087 42. 12 30. 43 Cement Cu conc 4. 541 29. 76 56. 02 Tail 93. 372 0. 7. 56

The pH value of the liquid from the telling was 4.8.

Example 1 0 A 1000 gram sample of the same copper ore as in Example 9 was reground wet for ten minutes and thereafter 'leached, at about 35% solids, with 36 grams of sulphuric acid to dissolve the oxidized copper, the resultant pulp being then filtered and washed once with water. The solids thus obtained were made up into a freely flowing pulp, which was agitated in the flotation ma.- chine with 0.1 lb. of General Naval Stores No. 5 pine oil per ton and 0.08 lb. of ethyl xantho molybdic acid per ten, the latter agent being added as a mixture obtained by adding a solution of sodium molybdate, acidified with hydrochloric acid, to a solution of sodium ethyl xanthate. Subsequently, a flotation concentrate was removed in the usual way. The following table indicates the results of the test:

Percent Assay, ier- Distribution, weight cent u percent Cu The pH value of the liquid from the tailing was 6.0.

Example 11 A 1000 gram sample of the same copper ore as in Example 9 was reground wet for ten minutes and thereafter leached with 36 grams of sulphuric acid to dissolve the oxidized copper. The dissolved copper was precipitated in the form of metallic copper by agitation with 20 grams of metallic iron, whereupon the pulp was subjected to flotation in the usual way, employing as reagents 0.1 lb. of General Naval Stores No. 5

pine oil, 0.1 lb. of Barrett No. 4 flotation oil, and 0.26 lb. of ethyl xanthomolybdic acid, all per ton of ore, theJast-jmentioned agent being added as a mixture obtained by admixing a solution of sodium molybdate', acidified with hydrochloric acid, with a solution of sodium "ethyl xanthate.

Both sulphides and cementcopper were simultaneously removed in this test, the results of which are shown in the following table:

. rmprrv alusozmw mnommunmgn ea;

Example 12 A 1000 gram sample of lo-mesh'Arizona Molybdenum Corporation ore.- containing both copper sulphides and molybdenite, was reground wet in the ball mill for fifteen minutes. Thereafter, the pulp was transferred to the flotation machine where it was treated for the production of a copper concentrate by employing as reagents 11b. of starch, 0.1 .lb. of sodium ethyl xan'thate, and 0.25 lb. of cresol, all per ton of ore, the usual conditioning period with these reagents preceding the irothing of the pulp.. With the material remaining was thenadmixed- 0.5 lb. oi' amyl xanthomolybdic acid per'ton, added as a. mixture obtained in the mannerdescribed belomtogether with 0.25 lb. of pinepoil per ton,- arougher molybdenum concentrateibeing. subsequently separated.- Upon removal of theztailing, this rougher concentrate was conditioned in the machine with 0.5 lb. of sodium cyanide'per ton-and 0.1'ib. of pine oil per ton, whereupon a final molybdenum concentrate .was obtained,- the of this cleaning operation constituting amolybdenum middling.

Theaiorementioned mixtm-e used in floating the rougher molybdenum concentrate was ob-- tained by first preparing a sodium molybdatesolution from a moiybdenite middling obtained in concentrating a com t-molybdenum ore, this middling being roasted and thereafter leached with sodium hydroxide solution. To the sodium molybdate solutionv thus obtained was added a potassium amyl xanthate solution in relative proportion of two molecules of'xanthate to one molecule of molybdate, hydrochloric acid being then added to the resultant solution to effect the reaction. In thus preparing the; mixture, the mixed solutions of xanthateand molybdate were employed in. quantities suillcient to form the aforestated 0.5 lb. of amyl xanthomolybdic acid per ton of ore. The results obtained in the above test are shown in the following table:

Assay percent Percent distribution On Mos; n MoS Heads 100.0 0. 020 l. x 100.0 100 0 0n Cone 4. 91 10. 80 l. 80. 75 0. 37 Mo Oonc. 1.22 0.38 91.60 0.73 74.34 Mold 3.01 1.84 6.10 10G) 14.66 90. 3 0.050 0. 077 7. 02 4. 63

Example 13 A rougher molybdenite concentrate containingabout 2.9% M08: and obtained by iroth flotation et a sample of ore from Utah Copper Company, from which sample a copper concentrate had al- I gamers '4 siss Distribution,

Percent Per a e mo [a m ,jioao s82 tans. can 04.18 .;o.11... ;1. V0.14 I

' w 94.2% mam s sli ea e stmmg with rousher mobbdenum concentrate of the same character as in Example 18,

the procedures of that example, with the butyl 'xanthomolybdic 'acidomitted and withthe cyanide used in'the last eightjof nine retreatments, gave afinalconcentrat'e of only 75.2% molybdenite, content thereinbeing 0.26%.

1. I 11m -11 1500 gram sample of Nevada Consolidated Copper Company ore, of a particle size to pass a IO-mesh screen and inthe form of a pulp of 50% solids, was reground for five and one-third minuteswith 5 lbs. of lime'per ton of ore. .The reground pulp was 'transferred'to the flotation machine, diluted to about 23 solida'andconditioned by; agitation with a' mixture'obtained by adding .a -hydrochloric-acid-acidified aqueous solution of sodium molybdate to :an aqueous solution; 01' potassium .phenyl-ethyl xanthate in such quantities asto producelili lb. of beta phenyl-, ethyl-'xanthomolybdic-acid per ton of ore. 881W.-

tion of-thepulp'being carried out with 0.06! lb. oi pine oil per ton'of ore. "lhereafter. frothing was out and the froth removed in the manner. The following tableshowsthere'sultsofthetestj 1 fare Distribution,

Percent percent 011 weight Example The procedures of Exampleli were repeated on another 1500 gram sample of the same copper ore, but increasing the amounts of acidified sodium molybdate and beta phenyl-ethyl xanthate so as to produce 0.08 lb. of phenyl-ethyl xanthomolybdic acid per ton of ore, eliminating the lime during grinding, and carrying out the conditioning of the pulp and subsequent irothing in a circuit made acid with 6.1 lbs. of sulphuric acid per ton of ore. The results of this test were as follows:

Percent Assay Distribut weight oent'd: percent 0 Heads 100.0 1.073 100.0 Cones 5. 39 l8. 1t 01. 18 Tells 94. 61 l0 8. 82

In each of the following three examples, the same xanthomolybdic acid compound was used, but was prepared with the use of a diil'erent organic acid as a solution-acidifying agent.

Example 16 I a 1500 gram sample of lo mesh Nevada 'Consolidated Copper Company ore was reground in the ball mill for five and one-half minutes with 1.5 liters of water and 7.5 grams of lime (equivalent to 10 lbs. per ton of ore). The material thus treated was transferred to the flotation machine where it was conditioned by agitation with 0.067 lb. of pine oil per ton and 0.04 lb. of ethyl xanthomolybdic acid per ton, the latter agent being prepared by acidifying a solution containing the required amounts of sodium molybdate and sodium ethyl 0 xanthate by means of acetic acid. Frothing was then carried out and the froth removed in the usual manner. The heads assayed 1.119% Cu, the concentrate 22.0% Cu, and the tailing 0.071% Cu, which represented a recovery of 93.95% of the total copper contained in the heads.

Example 17 The procedures of Example16 were repeated on another 1500 gram sample of the same copper ore,

20 but in this instance the ethyl xanthomolybdic acid was prepared with the use of furoic acid for acidifying the solution of sodium molybdate and sodium ethyl xanthate. The heads assayed 1.128% Cu, the concentrate 22.48% Cu, and the tailing 0.07% Cu, which represented a recovery of 5 94.08% of the total copper contained in the heads.

Example 18 Here the xanthomolybdic acid of Example 16 was prepared by adding oxalic acid to the solution of sodium molybdate and sodium-ethyl xanthate. All other conditions were exactly the same as in that-example. the test being carried out on still another 1500 gram sample of the same copper ore. The heads assayed 1.123% Cu, the concentrate 24.38% Cu, and the tailing 0.076% Cu, which represented a recovery of 93.52% of the total copper contained in the heads.

COMPARATIVE Tnsr 11 0 ways without departing. from its spirit.

What is claimed is:

1.. In the concentration of metalliferous ores by froth flotation, the step which consists in carrying out the froth flotation operation with the aid of a xanthomolybdic acid compound. 1

2. In the concentration of metalliferous ores by froth flotation, the step which consists in subjecting an-acid pulp of the ore to froth flotation in the presence of a xanthomolybdic acid.

3. In the concentration of metalliferous ores by froth flotation, the step which consists in effecting the froth flotation operation with the aid of a xanthomolybdic acid obtained from a soluble xanthate and a soluble molybdate by the action of an acid.

4. In the concentration of metalliferous ores by froth flotation, the step which consists in efiecting the froth flotation operation with the aid of a compound of the general formula M0O3.(RO.CSSH) 2.

wherein R is an alkyl or aralkyl group.

5. In the concentration of metalliferous ores by n froth flotation, the step which consists in effecting the froth flotation operation with the aid of a compound of'the general formula MOOS-(CnH2n+10-CSSH)2 wherein n is a wholenumber.

6. In the concentration of metalliferous ores by froth flotation, the step which consists in subjecting to froth flotation an aqueous pulp of the metalliferous ore admixed with a xanthomolybdic acid added thereto'in the state of solution in a m suitable solvent.

7. In the concentration of metalliferous ores by froth flotation, the step which consists in sub- Jecting to froth flotation an aqueous pulp of the metalliferous ore admixed with a xanthomolybdic 15 acid added thereto in the state of solution in acetone. v

8. In the concentration of metalliferous ores by froth flotation, the step which consists in c out the froth flotation operation with the aid of 20 the reaction product obtained by admixing in aqueous medium a soluble xanthate, a soluble molybdate, and an acid.

9. In the concentration of metalliierous ores by froth flotation, the step which consists in carrying out the froth flotation operation with the aid of the material obtainedby the action of an acid on admixed solutions of a salt of a xanthic acid and a salt of molybdic acid.

10. In the concentration of metalliferous 'ores by froth flotation, the step which consists in carrying out the froth flotation operation with the aid of the material obtained by the reaction in an aqueous medium of a soluble xanthate, a soluble molybdate, and a mineral acid, the said xanthate and moLvbdatebeing employed in relative proportions equivalent to two molecules of xanthic acid and one molecule of molybdic acid.

11. In the concentration of metalliferous'ores by froth flotation, the step which consists carrying out the froth flotation operation wi the aid of the material obtained by roasting a molybdenite ore, leaching the roasted ore with a solution of caustic alkali, and reacting the resultant iiquor with a soluble xanthate and an'acid.

12. In the froth flotation concentration of. molybdenum ores, the step which consists in effecting the froth flotation operation on the molybdenum ore by the aid of a xanthomolybdic acid 13. The process of concentrating ores containing molybdenite by froth flotation, which comprises admixing a pulp of the molybdenite-containing ore with a compound of the general formula M003.(C1:H2n+10-CSSH)3 where n is a whole number, treating the pulp by froth flotation so as to produce a concentrate rich in molybdenite, and separating the concentrate. 14. The processof concentrating ores containing copper and molybdenum sulphides, which 50 comprises subjecting a pulp oi such an ore to a treatment resulting in a removal of copper sulphide, treating by froth flotation the remaining pulp admixed with a xanthomolybdic .acid compound so as to produce a concentrate rich in 65 molybdenite, and separating the concentrate.

15. The process of concentrating ores containing copper and molybdenum sulphides, which comprises treating a pulp of such an ore in the presence of a flotation inhibitor of molybdenite 7 so as to separate a concentrate rich in copper sulphide; and treating the remaining pulp, after the addition of a xanthomolybdic acid compound thereto, so as to remove a froth flotation concentrate rich in molybdenite. u

16. The process of concentrating ores containing copper and molybdenum sulphides, which comprises treating a' Pulp of such an ore in the Patent No. 2,1i,g,i,75.y

presence of a protective colloid so as to remove a floating concentrate rich in copper sulphide, adding to the remaining pulp a xanthomolybdio acid compound, and thereafter treating the said remaining pulp by froth flotation so as to remove aconcentrate rich in molybdenite.

17. The process of concentrating ores containing copper and molybdenum sulphides, which comprises treating a pulp of such an ore in the presence of a flotation inhibitor of molybdenite so as to remove a floating concentrate rich in copper sulphide; and separating from the remaining pulp by froth flotation a molybdenite concentrate with the aid of the material obtained by the reaction in an aqueous medium of a soluble xanthate, a soluble molybdate, and an acid.

18. In the process of concentrating metallic copper by froth flotation, the step which consists in subjecting a pulp containing metallic copper to a froth flotation operation with the aid of a xanthomolybdic acid compound.

19. The process of concentrating ores containing sulphide and oxidized copper minerals, which comprises subjecting a pulp of such an ore to a treatment resulting in the separation by flotation of a concentrate rich in copper sulphide, leaching the remaining pulp with an acid to dissolve the oxidized copper, precipitating the dissolved cop per in the form of metallic copper, and treating the resulting material in the presence of a xanthomolybdic acid compound so as to separate by i'roth flotation a concentrate rich in metallic copper.

20. The process of concentrating ores containing sulphide and oxidized copper minerals, which comprises treating a pulp of such an ore with the aid of a xanthomolybdic acid compound so as CERTIFICATE or comics 3 It is hereby certified ELLER; v 7 that error appears in the printed specification to-separate by froth flotation a concentrate rich in copper sulphide, leaching the remaining pulp with an acid to dissolve the oxidized copper, precipitating the dissolved copper in the form 01' metallic copper, and treating the resulting material in the presence of a xanthomolybdic acid compound so as to separate by froth flotation a concentrate rich in metallic copper.

21. The process of concentrating ores containing sulphide and oxidized copper minerals, which comprises leaching such an ore with an acid to dissolve the oxidized copper, removing the solids from the dissolved copper, and treating a pulp of said solids in the presence of a xanthomolybdic acid compound so as to separate by froth flotation a concentrate rich in copper sulphide.

22. The process of concentrating ores containing sulphide and oxidized copper minerals, which comprises leaching such an ore with an acid to dissolve the oxidized copper, precipitating the dissolved copper in the form of metallic copper, sub- .iecting the resulting material to froth flotation in the presence of a xanthomolybdic acid compound so as to produce a concentrate rich in copper sulphide and metallic copper, and separating the concentrate.

23. In the concentration of metalliferous ores by froth flotation, the step which consists in carrying out the froth flotation operation with the aid of ethyl xanthomolybdic acid.

24. In the concentration of metalliferous ores by froth flotation, the step which consists in carrying out the froth flotation operation with the aid of amyl xanthomolybdic acid.

25. In the concentration of metalliferous ores by froth flotation, the step which consists in carrying out the froth flotation operation with the aid of butyl xanthomolybdic acid. CORNELIUS H.

CORRECTION. v February 28, 959- is: the above numbered patent requiring correction as follows: Page 5, second column, line 70:, injthe table, third column thereof," for the numeral "1 7513'. read 18,571; and that the said Letters latent should be read with this correction therein that the same may conform to the record of the case in the Patent Office. I

Signed and sealed this hth day of April, A. D. 1959.

(Seal) Henry Van Arsdale Acting Commissioner of Patents. 

